A technique relating to an external environment recognizing device for a vehicle has been developed in recent years. Such a device is configured to detect a moving object (obstacle) around a vehicle with a camera mounted on a vehicle, inform a driver of a risk of a collision between a vehicle and a moving object, and automatically stop the vehicle to avoid the collision between the vehicle and the moving object.
For example, an object detection device taught by Patent Literature 1 is configured to detect a moving object around a vehicle by processing an image captured by a camera having a fisheye lens.
A vehicle circumference monitoring device taught by Patent Literature 2 is configured to detect a moving object and a stationary object with optical flow detected from two original images captured at different times and a result of difference calculation between bird's-eye view images obtained through coordinate transformation of the two original images.